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Wednesday, November 2, 2011

Planet Dinosaur: Feathered Dragons

Besides DinosaurRevolution, the other big dinosaur documentary that came out this year was Planet Dinosaur. Naturally, this invites comparisons between the two, but, aside from both being about dinosaurs, they are really very different shows.

Though with scientific basis (and for most part accurate dinosaur models), Dinosaur Revolution is an experiment in storytelling that was unfairly shoehorned into a documentary format. Planet Dinosaur, on the other hand, is a bona fide dinosaur documentary. And I mean bona fide dinosaur documentary! Instead of putting a lot of focus into story or unsupported speculation, the real highlights of Planet Dinosaur are the cutaway segments throughout each episode that (get this) explain the fossil evidence for the behaviors its animals are shown engaging in and the form and function of each animal based on actual scientific research. Science in a dinosaur documentary, people! Take note, this is how a dinosaur documentary should be done, or at least it's a step in the right direction.

It's not that Planet Dinosaur doesn't engage in the occasional wild speculation now and then. It does. It's not that it gets everything right. It doesn't. But the fact it uses science as a focal point instead of an occasional aside or a way to make itself resemble a documentary makes it worthy of being a true documentary.

The first episode of Planet Dinosaur, "Lost World", focuses on two giant African theropods, the spinosaurid Spinosaurus and the carcharodontosaurid Carcharodontosaurus. It was a good start to the series, but there were no maniraptors in it.

The second episode, on the other hand, showcases maniraptors almost exclusively, and this is the episode I'll review here. Some spoilers ahead, even though plot isn't a big deal in this show.

A recurring theme throughout Planet Dinosaur is that it discusses mostly very recent dinosaur discoveries (made within the last decade). This episode, titled "Feathered Dragons", covers the discovery that some non-avian dinosaurs had feathers. The episode is split up into several segments that each features a different maniraptor taxon and talks about a different function feathers may have served in these dinosaurs.

First up is the strange Epidexipteryx, a possible basal avialian. One of the first scansoriopterygids on TV! It is shown escaping from a juvenile Sinraptor by climbing into the trees and hunting for grubs using its long third finger and unique dentition. It also encounters a rival Epidexipteryx and engages in a threat display using its four long strange tail feathers. It looked to me as though the Epidexipteryx had pronated hands in a number of shots, and we see its eyeball swiveling in its socket as it hunts. Modern birds can't do this, and that's why they often need to cock their heads at weird angles, which, confusingly, the Epidexipteryx is also shown doing. Otherwise though I have very little to nitpick (I want to say "pun intended" here, but I'd be lying) about this segment, though that might be at least partly because there isn't much about scansoriopterygids that we can even be reasonably certain of at the moment.

Next we see a Saurornithoides brooding its nest. Not a fan of Saurornithoides model, which lacks pennaceous feathers entirely and has only a very thin covering of feathers on the body, plumage befitting of a compsognathid perhaps, but not of a maniraptor. When the Saurornithoides leaves its nest temporarily, the nest is raided by an oviraptorid (which isn't specifically named). Evidence for omnivory in oviraptorosaurs is brought up, though unfortunately the evidence they put forth for predation (the discovery of hatchling Byronosaurus skulls in a Citipati nest) may soon fall victim to science marching on. This is of no fault of the show, as this data is still unpublished and has only been mentioned in a DML post, but they might have had better luck had they used the lizard in the body cavity of Oviraptor. The generic oviraptorid engages in some strange behavior of digging the eggs from the nest using its wing claws, in spite of the long wing feathers attached to its hands (which it commendably has). Digging using the feet as in modern ground-dwelling birds might have been more plausible, and indeed there is evidence of such behavior in Mesozoic aviremigians. Another anomaly regarding the oviraptorid is that even though it has wing feathers, they attach to the third finger (instead of the second as they should be). In fact, this is the case for every aviremigian in this show (or at least the ones that are lucky enough to have been given wing feathers).

Either way, the Saurornithoides manages to chase off the oviraptorid, only to be eaten by a much larger oviraptorosaur, Gigantoraptor, and the spotlight shifts. The show explains that large maniraptors might have kept feathers for display purposes, which is something straight out of the Gigantoraptor description paper. It's interesting that both Dinosaur Revolution and Planet Dinosaur have a sequence on the speculative display behavior of Gigantoraptor. The different approaches the two shows have are readily apparent: the Dinosaur RevolutionGigantoraptor is extremely flashy and extravagant with heavily speculative soft tissue structures, while the Planet DinosaurGigantoraptor is altogether more conservative. Aside from the wrong wing feather attachment, I quite like the ostrich-like plumage of the Planet DinosaurGigantoraptor and I find it quite plausible.

Finally, we get a sequence featuring the Jehol biota. There's a bit of anachronism here. We see a Microraptor hunting the gliding lizard Xianglong, and then being hunted itself by a Sinornithosaurus. The problem is that Microraptor is known only from the Jiufotang Formation, which is slightly younger than the Yixian Formation that Xianglong and Sinornithosaurus come from. I won't hold this too much against the show, as it is a common mistake. (It's even been made in the technical literature before!) In fact, even knowing that Microraptor is from the Jiufotang, I still find it hard to disassociate it from the Yixian. The Microraptor and Sinornithosaurus models are excellent, and aside from the usual wing feather attachment issue are some of the best deinonychosaur models on television I've seen to date, at least in terms of plumage. The chase scene that unfolds as the Microraptor tries to escape shows off (one of) the (hypothesized) gliding posture of Microraptor well. The legs looked a little splayed to me, but the show appears to have been going for Dr. Xu Xing's hypothesis presented in "The Four-winged Dinosaur" on Nova, and in any case there appears to be some possible evidence that microraptorines could splay their legs slightly more than other dinosaurs can. The really strange part in this sequence is that Sinornithosaurus is also shown to be capable of gliding, which is one of the few baseless speculations this show indulges in. Gregory Paul would be proud, I assume, but it appears that the wings of Sinornithosaurus were not large enough for actually gliding with (which is why there's hardly been any technical papers discussing the flight of Sinornithosaurus, as there has for Microraptor).

The last part of the show also happens to be the worst science wise. It features a trio of Sinornithosaurus hunting a family of the ornithopod Jeholosaurus. That alone isn't anything bad, and they even get in some impressively up-to-date info, namely the sclerotic ring study (published earlier this year) that indicates Sinornithosaurus may have been cathemeral, being active at intervals both in the day and at night. Things go downhill though when the Sinornithosaurus bring down one of the Jeholosaurus... using venom. That's right, the dreaded venomous Sinornithosaurus hypothesis. Granted, the show does use cautious qualifiers when dealing with the idea, but the fact that the Sinornithosaurus are actually shown in a way that endorses the hypothesis will probably leave a greater impact on laypeople than the narrative language. Frankly, in my opinion such fringe hypotheses should preferably not make their way into these serious documentaries at all, or only be mentioned to be dismissed as fringe hypotheses.

The show concludes with the concept that some feathered dinosaurs are still with us today, which of course is always a good idea to reinforce. Besides the venomous Sinornithosaurus slip up, this was a decent episode. As a dinosaur enthusiast it's easy (and, to be honest, fun) to nitpick and criticize, but I'll bet that most of the information presented here will be new to the average viewer and will greatly help in bringing them up to speed with the many wonderful new dinosaur discoveries made in recent years.

6 comments:

Is it just me, or do the eyes of PD's Saurornithoides not face forward as much as they should ( http://www.flickr.com/photos/10072627@N04/2588849492/ )? I ask you b/c you seem to have a good eye for detail. Many thanks in advance.

"but they might have had better luck had they used the lizard in the body cavity of Oviraptor."

Maybe, although it wouldn't have worked as well w/that scene, given that PD's oviraptorid was stealing troodontid eggs as opposed to hunting lizards.

"The generic oviraptorid engages in some strange behavior of digging the eggs from the nest using its wing claws, in spite of the long wing feathers attached to its hands (which it commendably has)."

Is that a reference to Senter 2006? That's what I thought of when I 1st watched that scene.

"which is why there's never been any technical papers discussing the flight of Sinornithosaurus, as there has for Microraptor"

When I 1st heard PD was gonna show said hypothesis, I felt more-or-less the same way The Nostalgia Critic does in the following link's vid. However, I actually liked the Sinornithosaurus/Jeholosaurus scene after having watched it (It probably helped that said hypothesis was shown as a possibility w/evidence as opposed to just being shown as fact).

I didn't intend to reference Senter specifically, but that is also the only paper I know that actually deals with whether or not the forelimbs in non-avian aviremigians could have been used for digging.

Wasn't aware of the gliding Sinornithosaurus in Chatterjee and Templin 2004; I'll edit the text accordingly.

Very good review, I couldn't agree with you more. I may add that the series' accompanying book gets the "venomous Sinornithosaurus" thing right and that it identifies the unnamed oviraptorid as Oviraptor (although it always struck me as Nemegtomaia). On a related note, I feel that the otherwise-perfect series could've used evolution sequences, a la Walking with Monsters.

I suppose either one would have worked, because the scene is anachronistic either way. Saurornithoides and Oviraptor are from the Djadochta Formation, some 10 million years earlier than Gigantoraptor and Nemegtomaia, from the Nemegt. Unless that was supposed to be "Saurornithoides" junior, aka Zanabazar. The Gobi desert formations have a long history of inappropriate taxon lumping, and the taxa are potentially separated by tens of millions of years. The ~5 million year or less Jehol lumping you see nowadays is nothing in comparison ;)